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Tham khảo tài liệu 'passive sampling techniques episode 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | MESCO for monitoring organic compounds in air membrane i.e. the time required for the analyte to pass the membrane. This lag time for the MESCOs of the type B 50 mm membrane thickness should be much shorter than for the MESCOs of the type A 250 mm membrane . The calculated lag times for the MESCOs A1 and A2 are in a range between 16 and 65h. The lag-times for the MESCOs B1 and B2 calculated from the results of the exposure experiments differ much more so that for these samplers no reliable values exist. Further investigations are necessary. 5.4.3 On-site exposure experiments The field exposure of the MESCO samplers A1 and A2 was performed according to the experimental conditions described above. To screen the site-relevant pollutants one of the loaded samplers was analysed by TDSA GC-MS with the MS operated in the scanning mode. Subsequently the other loaded samplers were analysed in SIM mode see Section 5.3 for selected relevant pollutants. Results of this field study are given in Table 5.3. The accumulated amounts of analytes are listed for both types of sampler at an exposure TABLE 5.3 Amounts of analytes accumulated in the receiving medium of the MESCO samplers of the type A Ms in ng exposed for 14 days on different sampling sites S in the area of the landfill Grube Antonie Compounda Sampler A1 Sampler A2 S1 S2 S3 S4 S1 S2 S3 S4 PTeCB 2.24 2.85 2.76 1.09 12.66 14.16 2.00 2.77 PeCB 0.82 0.79 1.19 0.50 4.33 3.61 0.86 1.19 HCB 0.71 0.68 0.74 0.67 2.54 1.70 1.63 2.62 a-HCH 57.2 220.8 63.4 22.4 599.3 2730.1 213.1 81.3 b-HCH 2.73 5.83 5.70 1.76 17.91 85.43 11.19 5.88 g-HCH 14.80 9.43 8.32 1.33 33.4 66.28 8.42 8.65 o p -DDE 0.81 0.81 0.84 0.79 1.89 1.81 3.61 1.06 Pjp -DDE 0.81 0.80 0.83 0.79 2.71 1.92 5.58 1.34 o p -DDD 0.81 0.78 0.80 n.d.b 3.13 1.88 1.93 1.10 pp -DDD 0.78 n.d. n.d. n.d. 2.06 1.70 1.67 0.89 o p -DDT 1.67 1.65 1.66 n.d. 8.60 8.23 11.23 2.79 pp -DDT n.d. n.d. n.d. n.d. 3.56 2.98 3.89 1.84 aDDD 1 1-dichloro-2 2-ồis chlorophenyl ethane DDE 1 1-dichloro-2
